U.S. patent application number 11/451253 was filed with the patent office on 2006-10-12 for air conditioning apparatus for vehicle.
Invention is credited to Kazushi Shikata, Kenji Suwa, Yukio Uemura.
Application Number | 20060225875 11/451253 |
Document ID | / |
Family ID | 36710413 |
Filed Date | 2006-10-12 |
United States Patent
Application |
20060225875 |
Kind Code |
A1 |
Uemura; Yukio ; et
al. |
October 12, 2006 |
Air conditioning apparatus for vehicle
Abstract
An interior of an air conditioning case is partitioned into a
first air passage extending from an inside air suction port to a
foot opening portion and a second air passage extending from an
outside air suction port is disposed at a side of the first air
passage to detect a temperature of air blown out from the
evaporator disposed in the first air passage and the second air
passage. An operation of the compressor for supplying the
refrigerant to the evaporator is intermitted by comparing the
temperature detected by the temperature sensor and the set
temperature set in advance, and the set temperature is changed to
be higher according to an increase in the temperature of outside
air. In this way, it is possible to prevent the frosting of the
evaporator in winter season, when the inside air is introduced into
the first air passage and the outside air is introduced into the
second air passage.
Inventors: |
Uemura; Yukio; (Kariya-City,
JP) ; Suwa; Kenji; (Kariya-City, JP) ;
Shikata; Kazushi; (Kariya-City, JP) |
Correspondence
Address: |
HARNESS, DICKEY & PIERCE, P.L.C.
P.O. BOX 828
BLOOMFIELD HILLS
MI
48303
US
|
Family ID: |
36710413 |
Appl. No.: |
11/451253 |
Filed: |
June 12, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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|
08950826 |
Oct 15, 1997 |
7082990 |
|
|
11451253 |
Jun 12, 2006 |
|
|
|
08872647 |
Jun 10, 1997 |
|
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|
08950826 |
Oct 15, 1997 |
|
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Current U.S.
Class: |
165/203 |
Current CPC
Class: |
B60H 1/321 20130101;
B60H 2001/3283 20130101; B60H 1/00849 20130101; B60H 2001/327
20130101; B60H 2001/3261 20130101 |
Class at
Publication: |
165/203 |
International
Class: |
B60H 1/00 20060101
B60H001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 19, 1996 |
JP |
08-340107 |
Dec 19, 1996 |
JP |
08-340182 |
Oct 16, 1996 |
JP |
08-273715 |
Jun 13, 1996 |
JP |
08-152721 |
Claims
1. An air conditioning apparatus for a vehicle having a passenger
compartment, said air conditioning apparatus comprising: an air
conditioning case having at one end thereof an inside-air suction
port for sucking inside air and an outside-air suction port for
sucking outside air and at the other end at least a first air
opening portion for blowing air toward a lower portion of the
passenger compartment and a second opening portion for blowing air
toward an inner surface of a windshield; a partition member for
partitioning an interior of said air conditioning case into a first
air passage extending from said inside-air suction port to said
first air opening portion and a second air passage extending from
said outside-air suction port to said second air opening portion; a
blower for blowing air in said first air passage and said second
air passage from said one end side to the other end side; a cooling
heat exchanger disposed in said first air passage and said second
air passage, for cooling air passing through said first air passage
and said second air passage; a temperature sensor disposed at a
side of said first air passage, for detecting a cooling temperature
of said cooling heat exchanger; adjusting means for adjusting a
refrigerant amount flowing into said cooling heat exchanger; and
adjusting control means for comparing a cooling temperature
detected by said temperature sensor and a set temperature and for
controlling operation of said adjusting means.
2. The air conditioning apparatus according to claim 1, wherein: a
heating heat exchanger disposed in said first air passage and said
second air passage at a downstream side of said cooling heat
exchanger, for heating air passing through said first air passage
and said second air passage.
3. The air conditioning apparatus according to claim 1, wherein:
said cooling heat exchanger is an evaporator of a refrigerant
cycle; and said refrigerant cycle includes a compressor for
compressing refrigerant, a condenser for condensing refrigerant
from said compressor, a decompression unit for decompressing
refrigerant from said condenser, and the evaporator for evaporating
refrigerant from said decompression unit.
4. The air conditioning apparatus according to claim 1, wherein
said temperature sensor is disposed in said first air passage at a
position immediately downstream from said cooling heat
exchanger.
5. The air conditioning apparatus according to claim 1, wherein
said adjusting control means control said adjusting means in such a
manner that, cooling operation due to said cooling heat exchanger
is performed when temperature detected by said temperature sensor
is higher than predetermined temperature, and the cooling operation
due to said cooling heat exchanger is stopped when the temperature
detected by said temperature sensor is lower than the predetermined
temperature.
6. The air conditioning apparatus according to claim 1, further
comprising: an inside air/outside air switching box for setting any
one of: an inside air/outside air double laminar mode in which
inside air is introduced into said first air passage and outside
air is introduced into said second air passage; an outside air mode
in which outside air is introduced into both said first air passage
and said second air passage; and an inside air mode in which inside
air is introduced into both said first air passage and said second
air passages.
7. The air conditioning apparatus according to claim 6, wherein:
said partition member has a communication path through which said
first air passage and said second air passage communicate with each
other; during said inside air/outside air double laminar mode, said
communication path is closed so that inside air from said
inside-air suction port is introduced into said first air opening
portion through said first air passage and outside air from said
outside-air suction port is introduced into said second opening
portion through said second air passage; during said inside air
mode, said communication path is opened so that inside air from
said inside air suction port is introduced into said second air
passage while being introduced into said first air passage through
said communication path.
Description
CROSS REFERENCE TO THE RELATED APPLICATIONS
[0001] This application is a divisional of U.S. application Ser.
No. 08/950,826 filed on Oct. 15, 1997 which is a
continuation-in-part of U.S. application Ser. No. 08/872,647 filed
on Jun. 10, 1997 and claims priority of Japanese Patent Application
No. Hei. 8-273715 filed on Oct. 16, 1996, the content of which are
incorporated herein by reference. The application is also related
to Japanese Patent Application Nos. Hei. 8-152721 filed on Jun. 13,
1996, Hei. 8-340107 filed on Dec. 19, 1996, and Hei. 8-340182 filed
on Dec. 19, 1996, also incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention relates to an air conditioning apparatus
having a first air passage and a second air passage, formed in an
air conditioning case, in which inside air and outside air are
introduced into the first air passage and the second air passage,
respectively.
[0004] 2. Description of Related Art
[0005] In a conventional air conditioning apparatus as disclosed in
JP-A-5-124426, there are formed at one end side of an air
conditioning case an inside air inlet for introducing inside air
and an outside-air inlet for introducing outside air and at the
other end side of the air conditioning case a foot air outlet for
blowing air toward a foot area, a defroster air outlet for blowing
air toward an inner surface of a windshield, and a face air outlet
for blowing air toward a face area.
[0006] In the air conditioning case, there is provided a partition
plate for partitioning an interior of the air conditioning case
into a first air passage extending from the outside-air suction
port to the face air outlet and the foot air outlet and a second
air passage extending from the outside-air suction port to the
defroster air outlet.
[0007] Further, in each of the first and the second air passages,
there are provided a cooling evaporator, a heating heat exchanger,
a bypass passage bypassing the heating heat exchanger, and an air
mixing door.
[0008] When any one of the face mode, the bi-level mode, and the
foot mode is selected as air outlet mode, if the inside air/outside
air introduction mode is set to the inside-air introduction mode,
the inside air is introduced into both air passages, whereas if the
mode is set to the outside-air introduction mode, the outside air
is introduced into both air passages.
[0009] Further, the foot mode is selected as the air outlet mode,
the inside air/outside air double laminar mode in which the inside
air is introduced into the first air passage and the outside air is
introduced into the second air passage is set. In this way, because
a passenger compartment is heated by a recirculation of the inside
air which has been already heated, the heating performance is
improved. Further, because the outside air having a low humidity is
blown toward the windshield, it is possible to obtain the
defrosting performance of the windshield certainly.
[0010] The inventors of the present invention have experimentally
produced the air conditioning apparatus having a function of the
above-described inside air/outside air double laminar mode, and
studied the control for preventing the frosting of the cooling
evaporator. As a result, it turns out that the following problem
occurs.
[0011] That is, in the air conditioning apparatus for a vehicle, as
being known well, an operation of the compressor for generating a
circulation of the refrigerant is intermitted according to the
cooling temperature of the cooling evaporator (more specifically
the temperature of the air just blown out from the evaporator) to
maintain the cooling temperature of the cooling evaporator at a set
temperature (e.g., 3.degree. C.-4.degree. C.). In this way, the
frosting of the cooling evaporator is prevented.
[0012] Here, as shown in FIGS. 11A and 11B in a case where a
temperature sensor 39 for detecting the cooling temperature of the
cooling evaporator 7 (more specifically the temperature of the
blown-air) is disposed in the inside-air passage (the first air
passage) 13, in summer season where the outside-air temperature is
high, the temperature of air blown from the cooling evaporator 7 in
the outside-air passage (the second air passage) 14 is higher than
that in the inside-air passage 13, as shown in FIG. 11A, because
the high-temperature outside air flows into the outside-air passage
14.
[0013] On the other hand, in winter season where the outside-air
temperature is low, as shown in FIG. 11B, the temperature of air
blown from the cooling evaporator 7 in the outside-air passage (the
second air passage) 14 is lower than that in the inside-air passage
13, because the low-temperature outside air flows into the
outside-air passage 14. Accordingly, in winter season, the cooling
temperature of the cooling evaporator 7 is lowered to be less than
0.degree. C. so that the evaporator may be frosted.
[0014] When the temperature sensor 39 is disposed in the
outside-air passage 14 as shown in FIGS. 11C and 1D, in summer
season when the outside temperature is high, the temperature of the
air blown from the cooling evaporator 7 in the inside-air passage
13 is lower than that in the inside-air passage 14, as shown in
FIG. 11C, because the low-temperature inside air flows into the
inside-air passage 13. Therefore, in order to prevent the frosting
of the cooling evaporator 7 in the inside-air passage 13 certainly,
a set temperature of the temperature sensor 39 needs to be higher
than the cases shown in FIGS. 11A and 11B by 5.degree. C.-6.degree.
C. for example.
[0015] However, if the set temperature of the temperature sensor 39
is set to be higher as described above, in winter season where the
outside-air temperature is low, the temperature of the blown-air in
the inside-air passage 13 is increased by 10.degree. C. for example
as shown in FIG. 1D, there occurs a problem that the dehumidifying
capacity for the inside-air is insufficient.
[0016] In view of the above-described problem, an object of the
present invention is to prevent the frosting of the cooling heat
exchanger in winter season certainly, which is mounted on the air
conditioning apparatus for a vehicle, having a first air passage
and a second air passage, formed in an air conditioning case, in
which inside air and outside air are introduced into the first air
passage and the second air passage, respectively.
[0017] Further, another object of the present invention is to solve
the insufficiency of the dehumidifying capacity for the inside air
in winter season.
SUMMARY OF THE INVENTION
[0018] According to the present invention, an interior of an air
conditioning case is partitioned into a first air passage extending
from an inside air suction port to a first opening portion and a
second air passage extending from an outside air suction port to a
second opening portion. A temperature sensor is disposed at a side
of the first air passage to detect a temperature of air blown out
from the cooling heat exchanger disposed in the first air passage
and the second air passage. A flow of the refrigerant into the
cooling heat exchanger is intermitted by comparing the temperature
detected by the temperature sensor and a set temperature set in
advance, and the set temperature is changed to be higher according
to an decrease in the temperature of outside air.
[0019] In this way, by intermitting the refrigerant flowing into
the cooling heat exchanger, the cooling temperature of the cooling
heat exchanger can be maintained at the set temperature so that the
frosting of the cooling heat exchanger is prevented. At that time,
since the set temperature is set to be higher according to the
decrease in a temperature of the outside air, it is certainly
possible to prevent a frosting of a part at the outside-air passage
side, of the cooling heat exchanger in winter season, which is
caused by the low-temperature outside air flowing into the outside
air passage.
[0020] That is, since the temperature sensor is disposed in the
first air passage, i.e., the inside-air passage, when the inside
air/outside air double laminar mode is set as the suction mode in
winter season, a part at the outside-air passage side, of the
cooling heat exchanger, may be frosted, because the low-temperature
outside air in introduced into the second air passage, i.e., the
outside-air passage, so that a temperature of the part at the
outside-air passage side, of the cooling heat exchanger, lowers to
be less than that of a part of the first air passage side; however,
since the set temperature relative to the temperature detected by
the temperature sensor is set to be higher in winter season as
defined above, the part at the outside-air passage side, of the
cooling heat exchanger, does not lower down to the frosting
temperature. In this way, it is possible to prevent the frosting of
the cooling heat exchanger.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Additional objects and advantages of the present invention
will be more readily apparent from the following detailed
description of preferred embodiments thereof when taken together
with the accompanying drawings in which:
[0022] FIG. 1 is a schematic cross sectional view for showing a
ventilation system of an air conditioning unit according to a first
embodiment of the present invention;
[0023] FIG. 2 is a cross sectional view, which is viewed from the
line II-II of FIG. 1;
[0024] FIG. 3 is a schematic cross sectional view, which is viewed
in a direction of an arrow III of FIG. 1;
[0025] FIG. 4 is an electrical block diagram of a control system in
the first embodiment;
[0026] FIG. 5 is a flow chart of a control process of a
microcomputer in the first embodiment;
[0027] FIG. 6 is a flow chart showing specifically a process of the
step 180 of FIG. 5;
[0028] FIG. 7 is a graph showing a relationship between an
outside-air temperature and a temperature of air blown out from an
evaporator in the air conditioning unit when a post-evaporator
temperature sensor is disposed at an inside-air side;
[0029] FIG. 8 is a front view showing an evaporator in the air
conditioning unit when a post-evaporator temperature sensor is
disposed at an inside-air side;
[0030] FIG. 9 is a graph showing a relationship between an
outside-air temperature and a temperature of air blown out from an
evaporator in the air conditioning unit when a post-evaporator
temperature sensor is disposed at an outside-air side;
[0031] FIG. 10 is a flow chart showing specifically a process of
the step 180 according to a second embodiment of the present
invention;
[0032] FIGS. 11A-11D are cross sectional views of a main portion of
a ventilation system in a conventional air conditioning unit;
[0033] FIG. 12 is a flow chart of a control process of a
microcomputer in a third embodiment;
[0034] FIG. 13 is a flow chart showing specifically a process of
the step 160 of FIG. 12;
[0035] FIG. 14 is a graph showing a relationship between an inside
air/outside air mode and a target air temperature according to the
third embodiment; and
[0036] FIGS. 15A and 15B are correlation diagrams between an
on-state and an off-state of a compressor and a temperature of
conditioned air according to the third embodiment.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0037] Referring to the drawings, preferred embodiments of the
present invention will be described.
[0038] A first embodiment of the present invention will be
described.
[0039] In this embodiment, each of air conditioning components in
an air conditioning unit for air conditioning a space in a
passenger compartment of a vehicle having a diesel engine mounted
thereon is controlled by an air conditioning control apparatus
(hereinafter referred to as "ECU".
[0040] Firstly, a construction of the air conditioning unit will be
described with reference to FIG. 1.
[0041] The air conditioning unit 1 is mounted on the vehicle in
such a manner that an upward direction of FIG. 1 is set to a front
direction of the vehicle (toward the engine), a downward direction
of FIG. 1 is set to a rear direction of the vehicle (toward the
passenger compartment), and a right-and-left direction of FIG. 1 is
set to a width direction of the vehicle. The air conditioning unit
1 is provided with an air conditioning case 2 for forming an air
passage for introducing conditioned air into the passenger
compartment.
[0042] The air conditioning case 2 is made of resin material such
as polypropylene and is constructed such that an inside air/outside
air switching box 3, a cooler unit 4, and a heater unit 5 are
connected to one another in this order from the air upstream
side.
[0043] The inside air/outside air switching box 3 is for
introducing at least one or both of inside air and outside air into
the air conditioning case 2. In the inside air/outside air
switching box 3, there is disposed a blower 6 for generating an air
flow. The inside air/outside air switching box 3 and the blower 6
will be described later with reference to FIG. 3.
[0044] In the cooler unit 4, there is disposed a refrigerant
evaporator for cooling blown-air in an entire area of the air
passage in the air conditioning case 2 to cross the air
passage.
[0045] The refrigerant evaporator 7 is a cooling heat exchanger for
cooling air by absorbing evaporation latent heat of the refrigerant
of refrigeration cycle. In addition to the evaporator 7, the
refrigeration cycle includes a compressor for compressing the
refrigerant by a driving force of the engine of the vehicle, a
condenser for cooling and condensing the refrigerant discharged
from the compressor 50, a receiver 52 for separating the
refrigerant condensed in the condenser into gas-phase refrigerant
and liquid-phase refrigerant, and a thermal expansion valve
(decompressing means) 53 for decompressing and expanding the
liquid-phase refrigerant from the receiver 52.
[0046] The compressor 50 is provided with an electromagnetic clutch
54 for intermitting a transmission of the driving force of the
engine of the vehicle. By intermitting an electricity supplied to
the electromagnetic clutch 54, an operation of the compressor 50
can be intermitted.
[0047] In the heater unit 4, there is disposed a heater core 8 for
re-heating cool air having passed through the refrigerant
evaporator 7. The heater core 8 heats air by using cooling water
(hot water) for cooling the engine of the vehicle as heat source.
As shown in FIG. 2, the heater core 8 is disposed in the air
conditioning case 2 in such a manner that a bypass passage 9 is
formed at a side of the heater core 8. The cool air passes through
the bypass passage 9 to bypass the heater core 8.
[0048] On an upstream side of the heater core 8, a rotary shaft 10
is rotatably disposed relative to the air conditioning case 2. To
the rotary shaft 10, two plate air mixing doors 11a and 11b are
connected in such a manner that each plate surface is disposed on
an identical plane. Further, to the rotary shaft 10, there are
connected servomotors 40 and 44 for driving the air mixing doors
11a and 11b.
[0049] When the rotary shaft 10 is rotated by the servomotor 40 or
44, the air mixing doors 11a and 11b are integrally rotated from a
position shown by the solid line to a position shown by the one-dot
chain line in FIG. 2. That is, since a ratio between an amount of
air cool air passing through the heater core 8 and an amount of air
passing through the bypass passage 9 is adjusted by selecting
rotational positions of the air mixing doors 11a and 11b so that
the temperature of air to be blown into the passenger compartment
can be adjusted, the air mixing doors 11a and 11b function as the
temperature adjusting means.
[0050] The inside air/outside air switching box 3, the cooler unit
4 and the heater unit 5 are detachably connected to one another by
connecting means such as claw fittings and screw members. In the
cooler unit 4 and the heater unit 5, as shown in FIG. 1, there is
formed a first air passage 13 and a second air passage 14 by a
partition wall 12 extending substantially in a perpendicular
direction. The refrigerant evaporator 7, the heater core 8, and the
rotary shaft 10 are disposed across the first air passage 13 and
the second air passage 14.
[0051] At the most downstream end of the air conditioning case 2,
there are formed a foot opening portion 15, a defroster opening
portion 16, and a face opening portion 17.
[0052] To the foot opening portion 15, there is connected a foot
duct (not shown), and the conditioned air introduced into the foot
duct is blown out through a foot air outlet formed at a downstream
end of the foot duct toward feet of a passenger in the passenger
compartment.
[0053] To the defroster opening 16, there is connected a defroster
duct (not shown), and the conditioned air introduced into the
defroster duct is blown out through a defroster air outlet formed
at a downstream end of the defroster duct toward an inner surface
of the front windshield of the vehicle.
[0054] To the face opening portion 17, there are connected a center
face duct (not shown) and side face ducts (not shown). The
conditioned air introduced into the center face duct is blown out
through a center face air outlet formed at a downstream end of the
center face duct toward an upper half of a body of a passenger at a
center portion in the passenger compartment. The conditioned air
introduced into the side face duct is blown through side face air
outlets formed at downstream ends of the side face ducts toward
side windshields or an upper half of a body of a passenger at a
right end portion or a left end portion in the passenger
compartment.
[0055] At upstream sides of opening portions 15-17, there are
respectively disposed a foot door 18, a defroster door 19, and a
face door 20 for intermitting an air flow into the opening portions
15-17, respectively. These doors 18-20 are connected by a link
mechanism (not shown), and the link mechanism is driven by the
servomotor 41 (see FIG. 4). By driving the link mechanism, each of
doors 18-20 is rotated to set each air outlet mode (described
later).
[0056] An air inflow passage into the side face duct is not opened
or closed by each of the doors 18-20. In the vicinity of the side
face air outlet, there is disposed an air outlet grille (not shown)
opened or closed by a manual operation of the passenger. With the
air outlet grille, the air to be blown out from the side air outlet
is opened or closed.
[0057] In the partition wall 12, at upstream sides of opening
portions 15-17, there is formed a communication port 21, through
which the first air passage 13 and the second air passage 14 are
communicated. The communication port 21 is opened or closed by the
foot door 18.
[0058] Next, constructions of the inside air/outside air switching
box 3 and the blower 6 will be described more specifically with
reference to FIG. 3. FIG. 3 is a schematic cross sectional view,
which is viewed in a direction of an arrow III of FIG. 1.
[0059] The inside air/outside air switching box 3 includes an
inside air/outside air case 3a constructing the air most upstream
side of the air conditioning case 2 and the blower 6 accommodated
in the inside air/outside air case 3a.
[0060] The blower 6 is disposed substantially at a center in the
inside air/outside air case 3a, and includes a first fan 6a, a
second fan 6b, and a blower motor 6c for rotating these fans 6a and
6b. The first fan 6a and the second fan 6b are integrally formed to
construct a centrifugal multi-blade fan. A diameter of the first
fan 6a is larger than that of the second fan 6b.
[0061] These first fan 6a and the second fan 6b are accommodated in
scroll casing portions 22 and 23, respectively. Each of scroll
casing portions 22 and 23 has a bell-mouth opening at a suction
side. Terminating end portions (air outlet side) of the scroll
casing portions 22 and 23 communicate with the first air passage 13
and the second air passage 14, respectively. The air passage in the
scroll casing portion 22 is partitioned from the air passage in the
scroll casing 23 by a common partition portion.
[0062] In the inside air/outside air case 3a, there are formed a
first inside-air suction port 26 corresponding to a suction port 25
of the first fan 6a and a second inside-air suction port 28 and the
outside-air suction port 29 corresponding to a suction port 27 of
the second fan 6b. In the inside air/outside air case 3a, there are
disposed a first suction port opening and closing door 30 for
opening or closing the first inside-air suction port 26 and a
second suction port opening and closing door 31 for selectively
opening or closing the second inside-air suction port 28 and the
outside-air suction port 29.
[0063] The first inside-air suction port 26 is formed at a position
closer to the suction port 25 as compared with the second
inside-air suction port 28. A position of the first suction port
opening and closing door 30 is controlled according to whether or
not the air mixing door is rotated to the maximum hot position (the
maximum heating position) as described later.
A position of the second suction port opening and closing door 31
is controlled according to the inside air/outside air mode.
[0064] To the first suction port opening and closing door 30 and
the second suction port opening and closing door 31 are connected
servomotors 42 and 43, respectively (see FIG. 4). Each of the first
suction port opening and closing door 30 and the second suction
port opening and closing door 31 is rotated between a position
shown by the solid line and a position by the one-dot chain
line.
[0065] In the inside air/outside air case 3a, there is formed a
communication passage 32 for communicating the second inside-air
suction port 28 or the outside-air suction port 29 with the suction
port 25. When fully opening the first inside-air suction port 26
(at the position shown by the solid line in FIG. 3), the first
suction port opening and closing door 30 fully closes the
communication passage 32, whereas when fully closing the first
inside-air suction port 26 (at the position shown by the one-dot
chain line in FIG. 3), the first suction port opening and closing
door 30 fully opens the communication passage 32.
[0066] Since the inside air/outside air switching box 3 is
constructed as above, by selecting positions of the first and
second suction port opening and closing doors 30 and 31, there is
set an outside-air suction mode in which outside air is introduced
into both of the first air passage 13 and the second air passage
14, an inside-air suction mode in which inside air is introduced
into both of the first air passage 13 and the second air passage
14, or an inside air/outside air double laminar mode in which
inside air is introduced into the first air passage 13 and outside
air is introduced into the second air passage 14.
[0067] In the first air (inside-air) passage 13, at an air outlet
side of the refrigerant evaporator 7, there is disposed a
post-evaporator temperature sensor 39 for detecting a temperature
of air blown out from the evaporator. The temperature sensor 39 is
composed of a thermal sensitive element such as a thermistor, and
generates a temperature detection signal to prevent the frosting of
the evaporator, as described later.
[0068] A construction of a control system of the embodiment will be
described with reference to FIG. 4.
[0069] To an ECU 33 for controlling each of air conditioning
components of the air conditioning unit 1, there is input each
signal of switches (e.g., a temperature setting switch for setting
a temperature in the passenger compartment by the passenger)
mounted on an operation panel 34.
[0070] To the ECU 33, there is input each signal of an inside-air
temperature sensor 35 for detecting a temperature of air in the
passenger compartment, an outside-air temperature sensor 36 for
detecting a temperature of outside air, a sunlight sensor 37 for
detecting an amount of sunlight entering the passenger compartment,
a water temperature sensor 38 for detecting a temperature of water
flowing into the heater core 8, and a post-evaporator temperature
sensor 39 for detecting a cooling temperature of the refrigerant
evaporator 7, more specifically, a temperature of air having just
passed through the evaporator 7.
[0071] In the ECU 33, there is provided a microcomputer (not shown)
including a CPU, a ROM, a RAM, and the like. When an ignition
switch (not shown) of the engine of the vehicle is turned on, an
electricity is supplied from a battery (not shown) to the ECU
33.
[0072] Further, while an air conditioning switch 34b is set on, the
ECU 33 controls an electric current supplied to the electromagnetic
clutch 7f such that, when the temperature detected by the
post-evaporator sensor 39 is equal to 3.degree. C. or less, the
compressor 7a is turned off, whereas when the temperature detected
by the post-evaporator sensor 39 is equal to 4.degree. C. or more,
the compressor 7a is turned on.
[0073] A control process of the microcomputer in this embodiment
will be described with reference to FIG. 5.
[0074] When the ignition switch is turned on and the electricity is
supplied to the ECU 33, a routine of FIG. 5 is started. At step
100, each of initialization and an initial setting are performed.
At next step 110, a set temperature set by the temperature setting
switch is input.
[0075] At step 120, each value of the sensors 35-39 is converted
from an analog signal to a digital signal and is read. Further,
whether the air conditioning switch 34b is turned on or off is also
read.
[0076] At step 130, a target temperature (TAO) of air to be blown
into the passenger compartment is calculated based on the following
formula (1), which is pre-stored in the ROM.
TAO=Kset.times.Tset-Kr-Kam.times.Tam.times.Ks.times.Ts+C (1)
[0077] wherein, Tset is a set temperature set by the temperature
setting switch, Tr is a value detected by the inside-air
temperature sensor 35, Tam is a value detected by the outside-air
temperature sensor 36, Ts is a value detected by the sunlight
sensor 37, Kset, Kr, Kam and Ks are gains, and C is a constant for
correction.
[0078] Next, at step 140, a blower voltage (a voltage applied to
the blower motor 6c) corresponding to the TAO is calculated from a
map (not shown) pre-stored in the ROM.
[0079] At step 150, an air outlet mode corresponding to the TAO is
determined from a map (not shown) pre-stored in the ROM. The air
outlet mode is determined to be a face mode, a bi-level mode, a
foot mode, and a foot/def mode in this order as the TAO
increases.
[0080] In the face mode, the foot door 18 is rotated to the
position shown by the one-dot chain line in FIG. 1, the defroster
door 19 is rotated to the position shown by the solid line, and the
face door 20 is rotated to the position shown by the one-dot chain
line, so that the conditioned air is blown toward the upper half of
the body of the passenger. In the bi-level mode, each of the foot
door 18 and the defroster 19 is rotated to the solid line, and the
face door 20 is rotated to the position shown by the one-dot chain
line, so that the conditioned air is blown toward both of the upper
half of the body and feet of the passenger.
[0081] In the foot mode, each of the foot door 18 and the face door
20 is rotated to the position shown by the solid line, and the
defroster door 19 is rotated to a position to slightly open the
defroster opening portion 16, so that approximately 80% of the
conditioned air is blown toward feet of the passenger and
approximately 20% is blown toward an inner surface of the front
windshield. In the foot/def mode, the foot door 18 is rotated to
the position shown by the solid line, the defroster door 19 is
rotated to the one-dot chain line, and the face door 20 is rotated
to the position shown by the solid line, so that the same amount of
the conditioned air is blown toward feet of the passenger and the
inner surface of the front windshield.
[0082] In this embodiment, when a defroster switch (not shown)
mounted on the operation panel 34 is operated, each of the foot
door 18 and the defroster door 19 is rotated to the position shown
by the one-dot chain line, and the face door 20 is rotated to the
position shown by the solid line, so that the defroster mode in
which the conditioned air is blown toward the inner surface of the
front windshield is set compulsorily.
[0083] In any one of air outlet modes, the side face air outlets
may be opened to blow the conditioned air; however, the side face
air outlets can be opened or closed by the air outlet grille.
[0084] At step 160, a target opening degree (SW) of the air mixing
doors 11a and 11b is calculated based on the following formula (2)
pre-stored in the ROM. SW=((TAO-Te)/(Tw-Te)).times.100 (%) (2)
[0085] wherein, Te is a value detected by the post-evaporator
temperature sensor 39, and Tw is a value detected by the water
temperature sensor 38. When the SW is calculated such that the
SW.ltoreq.0 (%), the air mixing doors 11a and 11b are rotated to
the positions where all of cool air from the refrigerant evaporator
7 passes through the bypass passage 9 (see FIG. 2). When the SW is
calculated such that SW.gtoreq.100 (%), the air mixing doors 11a
and 11b are rotated to the position where all of the cool air
passes through the heater core 8. When the SW is calculated such
that 0<SW<100 (%), the air mixing doors 11a and 11b are
rotated to the positions where the cool air passes through both of
the heater core 8 and the bypass passage 9.
[0086] At step 170, the inside air/outside air suction mode
(positions of the first suction port opening and closing door 30
and the second suction port opening and closing door 31) is
determined. More specifically, when the target temperature (TAO) of
air to be blown into the passenger compartment is equal to a
predetermined value or less, the inside-air suction mode is set.
When the TAO is equal to the predetermined value or more, either
one of the outside-air suction mode and the inside air/outside air
double laminar mode is selected.
[0087] That is, on the conditions where the TAO is equal to the
predetermined value or more, either one of the foot mode and the
foot/def mode is set, and the air mixing doors 11a and 11b are
controlled to the maximum heating position (i.e., the target
opening degree Sw is equal to 100 (%) or more such that all of cool
air passes through the heater core 8), the inside air/outside air
double laminar mode is selected. In contrast, even if the TAO is
equal to a predetermined value or more, when the air outlet mode is
set to the other mode or when the air mixing doors 11a and 11b are
not controlled to the maximum heating position, the outside-air
suction mode is selected.
[0088] At step 180, an on-state or off-state of the compressor 50
is determined. More specifically, as shown in FIG. 6, at step 180a,
set temperatures T1 and T2 for turning on or turning off the
compressor 50 are determined based on a detection value Tam of the
outside-air temperature sensor 36. Here, a hysteresis difference
shown at step 180b is given to the two set temperatures T1 and T2
to prevent a frequent switching between the on-state and the
off-state (a hunting phenomenon) of the compressor 50.
[0089] At step 180a, in winter season where the outside-air
temperature Tam is low, the set temperatures T1 and T2 are set in a
high area C (e.g., T1=5.degree. C., T2=6.degree. C.). In an
intermediate period of spring or fall, the set temperatures T1 and
T2 are set in an intermediate area B (e.g., T1=3.degree. C.,
T2=4.degree. C.). In summer season where the outside-air
temperature Tam is high, the set temperatures T1 and T2 are set in
a low area C (e.g., T1=2.degree. C., T2=3.degree. C.).
[0090] At the next step 180b, by comparing the set temperatures T1
and T2 set at step 180a and the detection value Te of the
post-evaporator temperature sensor 39, when the detection value Te
of the post-evaporator temperature sensor 39 lowers to be less than
the set temperature T1, the compressor 50 is turned off, whereas
when the detection value Te of the post-evaporator temperature
sensor 39 increases to be higher than the set temperature T2, the
compressor 50 is turned on.
[0091] At step 190, to obtain each of modes calculated or
determined at steps 140-180, control signals are output to each of
motors 6c and 40-43 and the electromagnetic clutch 54 of the
compressor 50.
[0092] At step 200, after a control cycle time .tau. has elapsed,
it returns to step 110.
[0093] In this embodiment, an operation of the compressor 50 is
turned on or off to maintain the detection value Te of the
post-evaporator temperature sensor 39 at the set temperature T1 or
T2 so that the frosting of the evaporator 7 is prevented; however,
since each of the set temperatures T1 and T2 is set to be higher in
accordance with a decrease of the outside-air temperature Tam as
shown at step 180a of FIG. 6, it is possible to certainly prevent
the frosting of a part of the evaporator 7, at the outside-air
passage (the second air passage 14) side, in wither season when the
low-temperature outside air flows into the outside-air passage.
[0094] That is, when the inside air/outside air double laminar mode
is set as the suction mode in winter season, a temperature of a
part of the evaporator 7, at the outside-air passage (the first air
passage 13) side, is lower than that in the inside-air passage (the
second air passage 14) side so that a part of the evaporator 7,
which is located in the outside-air passage, may be frosted;
however, in this embodiment, since the set temperatures T1 and T2
relative to the detection temperature Te of the post-evaporator
temperature sensor 39 disposed in the first air (inside-air)
passage 13, is set to be higher (e.g., T1=5.degree. C.,
T2=6.degree. C.) in winter season as described above, a part of the
evaporator 7, at the outside-air passage (the second air passage
14) side, does not lower down to the frosting temperature, so that
the frosting of the evaporator 7 can be prevented.
[0095] FIG. 7 is a graph of an experimental date, for showing that
the temperature of the air blown from an outside-air part of the
cooling evaporator 7 lowers in accordance with a decrease in the
temperature of the outside air. In this experiment, as shown in
FIG. 8, on conditions that the post-evaporator temperature sensor
39 is disposed at the inside-air side, and it is fixed that the set
temperature T1=3.degree. C. and the set temperature T2=4.degree.
C., each average value of the temperature of the air blown from an
inside-air part and the outside-air part of the cooling evaporator
7 is obtained by controlling an on-state or an off-state of the
compressor 50.
[0096] On the other hand, in summer season, since the set
temperature T1 and T2 relative to the detection temperature Te of
the post-evaporator temperature sensor 39 are set to be lower
(e.g., T1=2.degree. C., T2=3.degree. C.), the evaporator 7 performs
a cooling capacity sufficiently.
[0097] Further, in this embodiment, by disposing the
post-evaporator temperature sensor 13 in the first air passage 13,
the following effect can be obtained.
[0098] FIG. 9 is a graph of an experimental date, for showing that
the temperature of the air blown from the inside-air part of the
cooling evaporator 7 increases in accordance with a decrease in the
temperature of the outside air. In this experiment, on conditions
that the post-evaporator temperature sensor 39 is disposed at the
outside-air side, and it is fixed that the set temperature
T1=3.degree. C. and the set temperature T2=4.degree. C., each
average value of the temperature of the air blown from an
inside-air part and the outside-air part of the cooling evaporator
7 is obtained by controlling an on-state or an off-state of the
compressor 50.
[0099] Thus, when the post-evaporator temperature sensor 39 is
disposed at the outside-air side, as being understood from FIG. 11,
the dehumidifying capacity at the inside-air side in the
low-temperature outside-air area deteriorates. In contrast, when
the post-evaporator temperature sensor 39 is disposed at the
inside-air side, as being understood from FIG. 10, the
dehumidifying capacity at both of the inside-air side and the
outside-air side can be obtained certainly.
[0100] A second embodiment of the present invention will be
described.
[0101] The second embodiment differs from the first embodiment in
that the post-evaporator temperature sensor 39 is disposed at the
inside-air side of the evaporator 7 (in the second air passage 14)
and the process of step 180a in FIG. 6 is modified. The other
features are same as in the first embodiment.
[0102] As described above with reference to FIG. 10, when the
post-evaporator temperature sensor 39 is disposed at the
outside-air side (the second air passage 14) of the evaporator 7,
the temperature of air blown out from a part at the inside-air of
the evaporator 7 increases so that the dehumidifying capacity may
be deteriorated. In the second embodiment, as shown at step 180a'
of FIG. 7, in winter season where the outside-air temperature Tam
is low, the set temperatures T1 and T2 are set in a low area A
(e.g., T1=2.degree. C., T2=3.degree. C.). In an intermediate period
of spring or fall, the set temperatures T1 and T2 are set in an
intermediate area B (e.g., T1=3.degree. C., T2=4.degree. C.). In
summer season where the outside-air temperature Tam is high, the
set temperatures T1 and T2 are set in a high area A (e.g.,
T1=5.degree. C., T2=6.degree. C.).
[0103] As described above, in winter season, by setting the set
temperature T1 and T2 in the low area A, even when the
post-evaporator temperature sensor 39 is disposed at the
outside-air side of the evaporator 7, the increase in the
temperature at the inside-air side of the evaporator 7 can be
suppressed, so that the dehumidifying capacity at the inside-air
side can be obtained certainly.
[0104] Further, in this embodiment, by disposing the
post-evaporator temperature sensor 13 in the second air passage 14,
the following effect can be obtained.
[0105] That is, as being understood from FIG. 7, when the
post-evaporator temperature sensor 13 is disposed at the inside-air
side, if the outside-air temperature is extremely low, the
evaporator 7 may be frosted; however, when the post-evaporator
temperature sensor 13 is disposed at the outside-air side, as being
understood from FIG. 9, there is no possibility that the evaporator
7 may be frosted.
[0106] In each of the first and second embodiments, each of the set
temperatures T1 and T2 is changed by three steps of winter season,
intermediate period and summer season, according to the outside-air
temperature Tam; however, each of the set temperatures t1 and t2
may be changed by two steps of winter season and summer season.
[0107] Further, each of the set temperatures T1 and T2 is not
limited to be changed stepwise according to the; but may be changed
linearly according to the outside-air temperature Tam.
[0108] Still further, each of the set temperatures T1 and T2 may be
changed only in the inside air/outside air double laminar suction
mode.
[0109] Further, the present invention is employed in the air
conditioning apparatus in which a control for adjusting a
temperature of the air conditioning apparatus, setting a suction
mode, setting an air outlet mode, or the like, is performed by an
manual operation of the passenger.
[0110] In each of the first and second embodiments, the outside-air
temperature sensor 36 is employed as means for generating a signal
according to the outside-air temperature; however, it is not
limited to the outside-air temperature sensor 36, but may be
employed any kinds of means for generating a signal according to
the outside-air temperature, for example, the above-described
opening degree signal of the air-mixing door 11, a signal of the
target temperature TAO of blown-air, a calendar signal incorporated
in the microcomputer may be employed as the signal according to the
outside-air temperature.
[0111] Further, in each of the first and second embodiments, the
post-evaporator temperature sensor 39 is disposed at immediately
the downstream side of the evaporator 7; however, the
post-evaporator temperature sensor 39 may be directly attached to a
fin of the evaporator 7.
[0112] Still further, in each of the first and second embodiments,
in place of the heater core 8 using the cooling water for cooling
the engine as the heating source, there may be employed an electric
heater which heats when electrified, a condenser of the heat pump
type refrigeration cycle, or the like.
[0113] Further, in addition to the constructions in each of the
first and second embodiments, when a defroster switch (not shown)
mounted on the operation panel 34 is set, even if the air mixing
door 11 is not rotated to the maximum hot position, the first
suction port opening and closing door 30 may be rotated to the
position shown by FIG. 3. In this way, when the outside-air
introduction mode is set, the outside air is always introduced into
both of the air passages 13 and 14 so that the defrosting
performance of the front windshield can be improved.
[0114] A third embodiment of the present invention will be
described. Features which are different from the first embodiment
will be described.
[0115] In this embodiment, as being different from the first
embodiment, the air mixing doors 11a and 11b are independently
controlled and rotated by the servomotors 40 and 43.
[0116] This embodiment is different form the first embodiment in
the processes after step 160 in FIG. 5, and processes after step
160 will be described with reference to FIG. 12.
[0117] At step 160, each target opening degree (SW1 and SW2) of the
air mixing doors 11a and 11b is calculated. Hereinafter, the
content of step 160 will be described with reference to a flow
chart shown in FIG. 13.
[0118] First, at step 161, each temporary target opening degree SW
of the air mixing doors 11a and 11b is calculated based on the
following formula (3) pre-stored in the ROM. In this case, both of
the target opening degrees of the air mixing doors 11a and 11b are
SW. SW=((TAO-Te)/(Tw-Te)).times.100 (%) (3)
[0119] wherein Tw is a detection value of the water temperature
sensor.
[0120] When SW is calculated as SW.ltoreq.0 (%), the air mixing
doors 11a and 11b are controlled to positions where all of cool air
from the evaporator 7c passes through the bypass passages 9a and 9b
(see FIG. 1). When SW is calculated as SW.gtoreq.100 (%), the air
mixing doors 11a and 11b are controlled to positions where all of
cool air from the evaporator 7c passes through the heater core 8.
When SW is calculated as 0 (%)<SW<100 (%), the air mixing
doors 11a and 11b are controlled to positions where the cool air
passes through both of the heater core 8 and the bypass passages 9a
and 9b.
[0121] Next, at step 162, it is determined whether the air outlet
mode determined at step 150 is the foot mode (FOOT) or the
foot/defroster mode (F/D).
[0122] When the determination at step 162 is "YES", i.e., it is
determined that the air outlet mode is the foot mode or the
foot/defroster mode, it proceed to step 163, and it is determined
that the positions of the first suction port opening and closing
door 30 and the second suction port opening and closing door 31 are
set to the positions shown by the solid line in FIG. 3,
respectively. That is, it is determined that there is set the
double laminar mode where the inside air is introduced into first
air passage 13 and the outside air is introduced into the second
air passage.
[0123] On the other hand, When the determination at step 162 is
"NO", i.e., it is determined that the air outlet mode is the face
mode or the Bi-level mode, it proceed to step 163, and the inside
air/outside air mode is determined at step 163 from a graph in FIG.
14. Further, it proceeds to step 165, and it is determined that the
target opening degrees SW1 and SW2 are set to the target opening
degree SW calculated at step 161. It proceeds to step 170, and
control signals are output to obtain the control target value
determined at the above-described steps. Then, at step 190, after a
control cycle time .tau. has elapsed, it returns to step 110.
[0124] At step 163, when the double laminar mode is determined, it
proceeds to step 166, and it is determined whether or nor the
compressor 7a is turned off from the on-state. In this embodiment,
whether the compressor 7a is turned off from the on-state is
determined by operating the air conditioning switch (A/C S/W) 34b
by the passenger.
[0125] Further, in this embodiment, normally, when the flow chart
shown in FIG. 5 is executed, the compressor 7a is controlled such
that, when the detection temperature Te of the post-evaporator
sensor 39 is less than 3.degree. C., the compressor 7a is turned
off, whereas when the detection temperature Te of the
post-evaporator sensor 39 is more than 4.degree. C., the compressor
7a is turned on. The set value 3.degree. C. is set to prevent the
refrigerant evaporator 7a from being defrosted, so that the
capacity of the refrigerant evaporator 7a is prevented from
lowering.
[0126] As for the on-off control of the compressor 7a at 3.degree.
C. and 4.degree. C., once the air conditioning switch 34b is turned
on by the passenger, until the air conditioning switch 34b (or a
start switch for executing the flow chart of FIG. 5) is turned on
again, the compressor 7a is not turned on.
[0127] At step 166, when the determination "NO", i.e., the
compressor 7a has not been turned off from the on-state, and it is
determined that the compressor 3a is set on (when the compressor 3a
is turned on at 4.degree. C. and turned off at 3.degree. C.), it
proceeds to step 165. In this case, as shown in FIGS. 15A and 15B,
because the inside air and the outside air are cooled by the
evaporator 7c sufficiently, there is no great temperature
difference between the inside air and the outside air having just
passed through the evaporator 7c. Therefore, even if the opening
degree SW of the air mixing door 11b in the second air passage 14
is calculated based on the detection value of the post-evaporator
sensor 39 and SW2 is simply set to SW, there occurs no substantial
problem.
[0128] On the other hand, when the determination at step 166 is
"YES", i.e., the compressor 7a is set off, it proceeds to step 167.
At step 167, SW2 is not simply set to SW but is calculated
again.
[0129] That is, in this embodiment, because the post-evaporator
sensor 39 is disposed in the first air passage, the air mixing door
11b in the second air passage 14 cannot be controlled based on the
detection temperature of the post-evaporator 39.
[0130] That is, if it is assumed that the inside air temperature is
25.degree. C. and the outside air temperature 10.degree. C., as
shown in FIG. 8, the compressor 7a is turned off from the on-state.
Further, if the off-state is continued for a long time, because the
refrigerant is not supplied into the evaporator 7c, the cooling
capacity of the evaporator 7c lowers. Therefore, if it is
considered that there is no cooling capacity, the detection
temperature of the post-evaporator sensor 39 is 25.degree. C.
[0131] Therefore, although the actual temperature of the air having
just passed through the evaporator 7c in the second air passage 14
is 10.degree. C., the air mixing door 11b is controlled based on
that the temperature of the air having just passed through the
evaporator 7c in the second air passage 14 is determined as
25.degree. C. As a result, if the target opening degree of the air
mixing door 11b is calculated based on detection temperature of the
post-evaporator sensor 7c, the temperature of the conditioned air
in the second air passage 14 is controlled to be lower than the
target air temperature.
[0132] To overcome this problem, at step 167, the target opening
degree of the air mixing door 11b is corrected to the opening
degree calculated based on the detection temperature when the
post-evaporator sensor 39 is disposed in the second air passage
14.
[0133] At step 167, a correction amount .DELTA.SW2 of the air
mixing door 11b is determined. At step 167, as shown in FIG. 13,
the larger the difference between the inside air temperature Tr and
the outside air temperature Tam is, the lower the temperature of
the conditioned air in the second air passage 14 relative to the
target air temperature is. Therefore, the correction amount
.DELTA.Sw2 is set larger in accordance with the difference.
[0134] Then, it proceeds to step 168, the target opening degree SW2
of the air mixing door 11b is calculated by adding the correction
amount .DELTA.SW2 to the SW, and SW1 is set to the SW.
[0135] When the compressor 7a is turned off from the on-state,
because the cooling capacity of the evaporator 7c gradually lowers,
the detection temperature of the post-evaporator sensor 39
approaches 25.degree. C. To overcome this problem, at step 168, the
correction amount .DELTA.SW2 is set as described above, and the
target opening degree is gradually corrected by the .DELTA.SW2
within a predetermined time t (sec.) to cancel the decrease of the
temperature of the conditioned air.
[0136] In this way, when the compressor 7a is turned off from the
on-state, the temperature of the conditioned air in the second air
passage 14 is controlled in the same manner as when the
post-evaporator sensor 39 is disposed in the second air passage 14,
and as compared with a case when the opening degree is calculated
based on the detection value of the post-evaporator 39 by the
formula (3), the temperature of the conditioned air can be
prevented from lowering.
[0137] A fourth embodiment of the present invention will be
described.
[0138] In the third embodiment, the post-evaporator sensor 39 is
disposed in the first air passage 13; however, in this embodiment,
the post-evaporator sensor 39 is disposed in the second air passage
14.
[0139] The fourth embodiment is different from the third embodiment
in the control at steps 167 and 168, and this control is shown as
steps 169 and 171 in FIG. 13.
[0140] If the post-evaporator sensor 39 is disposed in the second
air passage 14, and the SW1 is set to SW based on the detection
value of the post-evaporator sensor 39, as compared with a case
when the post-evaporator sensor 39 is disposed in the first air
passage 13, the air mixing door 11a is controlled to increase the
temperature of the conditioned air in the first air passage 13.
[0141] Further, as described above, when the compressor 7a is set
on (when the compressor 3a is turned on at 4.degree. C. of the
detection temperature of the post-evaporator sensor 39 and turned
off at 3.degree. C.), there is no great temperature difference
between the inside air and the outside air having just passed
through the evaporator 7c. Therefore, even if SW1 is simply set to
SW, there occurs no substantial problem.
[0142] However, when the compressor 7a is turned off from the
on-state, the cooling capacity of the evaporator 7c gradually
lowers. Therefore, the detection temperature of the post-evaporator
sensor 39 approaches 10.degree. C. Accordingly, in this case, when
SW1 is set to SW based on the detection temperature of the
post-evaporator sensor 39, the temperature of the conditioned air
becomes higher than the target air temperature TAO.
[0143] At step 169, the correction amount .DELTA.SW2 of the opening
degree of the air mixing door 11a is determined. At step 169, as
shown in FIG. 13, the larger the difference between the inside air
temperature Tr and the outside air temperature Tam is, the higher
the temperature of the conditioned air in the first air passage 13
relative to the target air temperature is. Therefore, the
correction amount .DELTA.SW1 is set larger in accordance with the
difference.
[0144] Then, it proceeds to step 171, the target opening degree SW1
of the air mixing door 11a is calculated by subtracting the
correction amount .DELTA.SW1 from the SW, and SW2 is set to the
SW.
[0145] When the compressor 7a is turned off from the on-state,
because the cooling capacity of the evaporator 7c gradually lowers,
the detection temperature of the post-evaporator sensor 39
approaches 10.degree. C. To overcome this problem, at step 171, the
correction amount .DELTA.SW1 is set as described above, and the
target opening degree is gradually corrected by the .DELTA.SW1
within a predetermined time t (sec.) to cancel the increase of the
temperature of the conditioned air.
[0146] In this way, when the compressor 7a is turned off from the
on-state, the temperature of the conditioned air in the first air
passage 13 is controlled in the same manner as when the
post-evaporator sensor 39 is disposed in the first air passage 13,
and as compared with a case when the opening degree is calculated
based on the detection value of the post-evaporator 39 by the
formula (3), the temperature of the conditioned air in the first
air passage can be prevented from lowering.
[0147] In the above-described embodiments, by the air conditioning
switch 51 manually operated by the passenger, it is determined at
step 166 that the compressor 7a is turned on from the off-state;
however, for example, in an air conditioning apparatus for a
vehicle, in which the compressor 7a is compulsorily turned off
while the vehicle is accelerating, it may be determined that the
time period during which the compressor 7a is set off while the
vehicle is accelerating is continued for a predetermined time.
[0148] In the above-described embodiments, in the foot mode or
foot/defroster mode, the opening degrees of the air mixing doors
11a and 11b are corrected; however, for example, in the bi-level
mode, the inside air is introduced into the first air passage 13,
the outside air is introduced into the second air passage 14, and
the opening degrees of the air mixing doors 11a and 11b may be
corrected differently.
[0149] In the above-described embodiments, the temperature of the
conditioned air is adjusted by the air mixing doors 11a and 11b;
however, the present invention may be employed in an air
conditioning apparatus for adjusting the temperature of the
conditioned air by adjusting an amount of hot water flowing into
the heater core 8.
[0150] Although the present invention has been fully described in
connection with the preferred embodiments thereof with reference to
the accompanying drawings, it is to be noted that various changes
and modifications will become apparent to those skilled in the art.
Such changes and modifications are to be understood as being
included within the scope of the present invention as defined in
the appended claims.
* * * * *